1. Field of the Invention
The present invention relates generally to heat exchanger closure connections, and more particularly to a heat exchanger closure connection having shellside and tubeside seals held together by a common flange with common or separate bolts which allows removal of the tubeside connection and seal without removal of the shellside connection and seal.
2. Description of the Prior Art
As the name implies, heat exchangers are devices for transfering heat energy. Typically, such transfer is from one fluid to another. One common variety of heat exchange device is the double pipe heat exchanger which includes an outer pipe or shell which carries one of the fluids and one or more inner pipes or tubes which carries the other fluids. The space interior of the shell and exterior of the tubes is referred to as the shellside and the space within the tubes is referred to as the tube side.
There have been developed a number of closures for establishing sealing inner connections in double pipe exchangers. For example, in U.S. Pat. No. 3,424,480, there is disclosed a double seal closure connection which is adapted to establish a shellside connection and a tubeside connection with a common set of bolts holding the connections together. One disadvantage of the closure connection of the '480 patent is the fact that the common set of bolts is subjected to differential temperatures and pressures and to various vibrations or pulsations. Thus, environmental conditions that affect one of the seals also affect the other seal, thereby making the seals interdependent. A further disadvantage in the construction of the closure connection of the '480 patent is in that the tubeside connection and seal cannot be broken without also breaking the shellside connection and seal. Such further disadvantage manifests itself when it becomes necessary to clean or inspect the tubeside, which involves opening the tubeside connection. Since the tubeside connection cannot be opened without also opening the shellside connection, the entire exchanger must be taken out of service.
In U.S. Pat. No. 3,593,782 there is disclosed a heat exchanger closure connection which has separate shellside and tubeside closures. Thus, the closure seals are independent of each other and tubeside connection can be dismantled to allow cleaning or inspection of the tubeside without disturbing the shellside closure. Likewise, the shellside seal may be inspected without disturbing the tubeside seal. However, the construction of the closure of the '782 patent requires more than a single set of bolts or the like for assembly, and accordingly, is more expensive to produce than the closures of the type exemplified by U.S. Pat. No. 3,424,480.
It is therefore an object of the present invention to provide a heat exchange closure connection which overcomes the shortcomings of the prior art. More specifically, it is an object of the present invention to provide a heat exchange closure connection which establishes independent shellside and tubeside closures with a common flange using either common or separate sets of bolts.